1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that each include a pressure generating chamber communicating with a nozzle aperture, and a piezoelectric element changing the pressure in the pressure generating chamber and including a piezoelectric layer and electrodes applying a voltage to the piezoelectric layer, and to the piezoelectric element.
2. Related Art
Some of the piezoelectric elements have a structure in which a piezoelectric layer made of a piezoelectric material capable of electromechanical conversion, such as a crystallized dielectric material, is disposed between two electrodes. This type of piezoelectric element can be used as a deflection vibration mode actuator device in a liquid ejecting head. Ink jet recording heads are a typical type of liquid ejecting head. An ink jet recording head includes a vibration plate defining a part of a pressure generating chamber communicating with a nozzle aperture through which ink droplets are ejected. In the ink jet recording head, a piezoelectric element deforms the vibration plate to apply a pressure to the ink in the pressure generating chamber, thereby ejecting ink droplets through the nozzle aperture.
The piezoelectric material (piezoelectric ceramic) used for forming the piezoelectric layer of such a piezoelectric element is required to have high piezoelectric properties, and a typical example of the piezoelectric material is lead zirconate titanate (PZT) (see JP-A-2001-223404). On the other hand, it is desired to reduce lead from piezoelectric materials, from the viewpoint of environmental protection. For example, BiFeO3-based piezoelectric materials, which contain Bi and Fe, are lead-free. Among these are piezoelectric materials containing mixed crystals of Bi(Fe, Mn)O3 and BaTiO3 (see JP-A-2009-252789).
Since the piezoelectric element used in such an ink jet recording head or the like is repeatedly operated while causing displacement, the piezoelectric layer is subject to the risk of separating from the electrodes. This issue arises not only in ink jet recording heads that eject ink droplets, but also in other liquid jet heads that eject droplets other than ink.